body {
  padding: 0;
  margin: 0;
}

.nav_bar {
  display: flex;
  margin-bottom: 20px;
}

.nav_bar div {
  text-align: center;
  height: 40px;
  line-height: 40px;
}

.nav_center {
  flex: 1;
  background-color: sandybrown;
}
.nav_left, .nav_right {
  width: 50px;
  background-color: rosybrown;
}